Apparatus for determining the speed of rotation of impulse-transmitters.



' A. H. ADAMS.

APPARATUS FOR DETERMINING THE SPEED 'OF ROTATION 0F IMPULSE TRANSMITTERS.

' APPLICATION FILED DEC. 25. 1914. m, 4.

' Patenfed Nov. 16, 1915.

2 SHEETS5HEET l.

/nveMf0/ Alfb/V hf Adams A. H'. ADAMS. APPARATUS FOR DETERMINING THE SPEED or ROTATiON 0F iMPULSE TRANSMITTERS.

APPLICATION FILED DEC- 26. I914.

Patnted Nov. 16, 1915.

2 SHEETS-SHEET 2- /nver17or Amhw l7! Adams l V/Tnesses:

ARTHUR H. ADAMS, or SPARKILL, nnwyoax, A-SSIGNOR 'ro wnsrniiar' nnnc'rnrc COMPANY, or new YORK,N. Y., A conronnrron or ILLINOIRQ APPARATUS FOR DETERMININ G THE SPEED OF RbTATION OF IMPULSE-TRANSMITTERS icense.

larlyto improved method and means whereby it may be readily and accurately determined whether the speed of operation of such impulse transmitting mechanisms is within the maximum and minimum speed limits necessary for the proper operation of the automatic switching apparatus in thetelephone exchange with wh1ch the substation, at which such impulse transmitting mechanism is located, is associated.

In automatic telephone exchange installations, great difiiculty. has been experienced in adjusting and maintainin the speed oi operation of the subscribers impulse transmitters or finger wheels within such limits of speed both maximum and minimum as will produce the proper and accurate operation of the automatic switches at the exchange, by which the calling line in response to the operation of such impulse transmitter or finger wheel is extended to a desired line. This difiiculty is particularly met with when the impulse mechanism or finger wheel is installed in the substation, although it is none the less met with when, after assemvbly, the im also mechanism or finger wheel isbeing ad usted before installation. It has been the practice heretofore when the finger wheel is already installed and trouble has been experienced with it, which indicates] that it is running either too fast or too'siow,"

to connectthe line with whic'hsuch finger wheel isassociated toa'step-by-step switch or similar piece of appa-ratus'upona Wire ehiefs desk in the central ofice, and the finger wheel being then operatedeb an inspector at the substation, the wire 0 ief w 11 report whether the operat on oft/such fing r Specification of Letters Patent;

Application filed December 26, 1914. Serial No. 878,164.

terminin methods have been tried and foun the disk and the large Patented Nov. 16, 1915,

wheel is either too fast or too slow, the inspector from time to time in response to the reports of the wire chief, changing the tens1on of the operating spring of the-finger wheel, or the friction of the governor which controls its movement, until the finger wheel rotates at such a speed that it satisfactorilyfoperates the switch before the wire chief.

Substantially the same procedure .has been required in testing impulse mechanisms of,

this character after assembly and before installation. Obviously this method of deand adjusting the'speed of finger wheels Q y extended experimentation is clumsy, inefficient, an'dunsatisfactor Other d unsatisfactory, as vfor exampletheuse of a stopwatch to measure the speed of movement of the finger disk, which method, owing to the relatively short dura't on of movement of ersonal equation entering into this mode of measurement, has

been found ineiiicient and inaccurate. One ofthe features of the presentinvention is to provide a method and apparatus whereby it may be instantly determined whether the speed ofthe movement of the impulse transmitter or finger Wheel is with-c in'the necessary maximum or minimum lim its, or ifiit is not within such limits, whether 'itis above the required maximum limit or below the required minimum limit. Further, by means of the present invention, no

connection of the impulse transmitterunder test is necessary with any: switch, in fact no electrical connections are necessary at all in connection with the test, and only such tools are required as may be readily carried by an inspector to the subscribers' station, and the test may be made without in any way disturbin the subscribers line or interfering with the such line during the test.

@hnother distinctive feature of the invenreception of incoming calls over tion is that it provides a method for the" purpose described which eliminates 1 entirely any personal equation of the person making the test and leaves no room for improperpersona judgment or error.

Referring to the drawings-Figure 1 shows in perspective themanner in which the improved method and apparatus em b'odying the invention herein may be utilized. Fig. 2 represents an indicator card such'as -.is used in the test illustrated in Fig. 1. Fig. 3 shows a modifiedform of indicator card. Fig. 4 shows a modification of the invention in which no indicator card is necessary, the function of the indicator card being combined with the fingerv disk of the impulse transmitter itself. Fig.

, nection between the variousparts referred wardly, toward to, and between the "substation set and the central exchange, since they are not necessary for an understanding of the present invention, are not shown, and will not be described. v

15 represents an indicator card which may be attached by any desired means to the finger diskof the impulse transmitter 10. This indicator is formed of a circular piece of cardboard of substantially the same size as the finger disk of the impulse transmitting mechanism. It is provided on its face with circumferentially arranged printed or stamped projections 16, as shown, such projections extending inthe center of the disk. Somewhat n'earerKthe center. of the disk than the projections 16,- the disk is pro vided with circularly arranged outwardly extending printed or stamped projections 17. The disk is also provided with a finger hole 18- which will usually, in the use of the disk, be placed adjacent the opening on the finger disk of the impulse transmitter most removed from the stop position of such impulse transmitter when the finger disk thereof 'is moved in a clockwise direction in the operation of the impulse transmitter to send a digit of the desired line.

It has been found that the speed at which impulse transmitting mechanisms of the type referred to operate at greatest efficiency is at the rate of twelve impulses per second. In impulse transmitting mechanisms of the type. of which the finger disk 1s shown in Fig. 4 this gives avspeed of rotation of such finger disk of 24/25ths of a revolution per second. It has been further determined by careful experiment that safe maximum and minimum speeds of rota t1on of finger disks of this type are'respectively 25/ 25ths of a revolution per second and 22/25ths of a revolution per second. 1 I

. The indicator card 15, or in the modified form the indicator card'15, or the finger disk itself 19 as shown in Fig. 4, are therefore provided with 110 outwardly. extending printed or stamped projections 17 and with 125 inwardly extending printed or stamped that they should be readily visible and preferably, therefore, should be of contrasting color to the card or disk upon which they appear.

A To cooperate with the card or disk in the test there is provided a tuning fork 20 as shown in Figs. 1 and 5, such tuning fork having attached respectively to the ends of its vibrating arms the shutters 21,22. Each of these shutters has formed therein a slit, respectively 23 and 24, which are adapted to register with each other, when the fork is vibrating, twice for each cycle of vibration of such fork. These slits are therefore preferably arranged that when the fork is not in vibration they register approximately with each other, but when the fork is vibratingthey register with each other for a brief period twice only during a cycle of vibration. In Fig. 5, in order to show the construction more clearly, the slits are shown out of alinement in the position in which they would. be when the vibrating arms of'the tuning fork are nearest to each other in .a cycle of vibration.

In order to coeperate with the particular arrangement of the printed or stamped projections upon the cards or finger disks the tun'ing'fork should have a periodicity of 55 cycles per second. When this fork is caused to vibrate in the usual manner, the openings 23, 24 in the shutters 21, 22 will register with each other 110 times per second.

The apparatus heretofore referred to is used in the test in the manner of the wellknownstroboscope. The observer having started the tuning fork in vibration rotates" ,moved to its full extent in such direction.

He then releases the finger disk, and ohserves through the slits 23, 24 on the tuning fork-the movement of the printed or stamped projections upon the card or disk.- The movement of the disk or card at this time is in a counter-clockwise direction. If

the disk or card is moving at this time at a rate of speed precisely '25/25ths of a revolution per second, the printed or stamped projections 17 as viewed through the alined slits of the tuningv fork will be standing still. This is for the reason that such printed or stamped projections 17, each occupy an arc 'of l/llOth of the circle on'which they are forined,and as the observer obtains limpses J position that the preceding tooth was at his:

last glimpse. No movement, therefore, of the projections 17 will be apparent to the observer if, as assumed, the speed of rotation of the card or disk is at precisely the rate of /25ths of a revolution per second. At. this same speed the projections 16 as they each occupy an arc of 1/125th of the circle on which they are formed will appear to be moving in a' counter-clockwise direction, since between each two glimpses obtained by the observer of such projections 16 the card or disk'will have moved not only the angular displacement of one of such projections, but

also in addition the displacement of a naetion of one of such projections. At the assumed speed, therefore, that is, the speed of 25/25ths of a revolution per second, the projections 17 will appear to the observer to be standing still, and the projections 16 to be moving in a counter-clockwise direction. If the speed of rotation of the card or disk is v greater than the allowed maximum, not only will theprojections 16 appear to be moving m a counter-clockwise direction, but since the card or disk moves a trifle more than the angular displacement of one of the projections 17 between each two glimpses of the card or disk by the observer, such teeth 17 will also appear to be moving in a counterclockwise direction. In this case the observer will know that the speed of rotation of the finger disk and the consequent operation of the impulse producing mechanism is too great. Assuming on the other hand, that the speed of rotationof the finger disk is at'the rate'of 22/25ths of a complete rotation per second, which is the minimum desired speed, the observer will detect no movement in the projections 16 since the movement of the card or disk under the present assumption is such that between eachtwo glimpses by the observer of the projections 16, the disk has moved just the angular displacement of one of such projections 16'. On the other hand at the speed assumed, the

projections 17 will appear to the observer to v be moving in a clockwise direction as be tween each two glimpses by the observer the card or disk hasnot moved quite the angular displacement ofone of the projections 17,

. therefore, the observer gazing at a particular point will at one glimpse see at such point a" f 4 projection 17, and atthe next glimpse will see the next projection 17 almost moved into the position in which he'saw the first projection referred to, but since it has not quite reached it, it will appear to the observer as though the projectionwhichhe first saw had moved" slightly in a clock-wise. direction.- Therefore, at the desired speed it i c'eed in the usual manner will be apparent that to the observer the projections 16 will be without motion, whereas the projections 17 will appear to be moving in. a clock-wise direction. If the-speed of rotation of the. card or diskis below the minimum desired speed, both such sets of projectionswill appear. tozbe'moving a clock-wise direction, naturally the pro ections 17 at a higher speedthan the projections 16. Obviously such motion in a clockwise direction is apparent and not real.

If the speedof the impulse transmitting mechanism under observation is between the maximun. and limits referred to, the projections 16 upon the card or disk will appear to be moving in acounter-clocking more than'the angular displacement of one of such projections 16 betweeneach two glimpses by the observer, and the projec tions 17 will appear to be moving in'a clockwise directionv since the angular displace.

ment of the card or disk between each two- ,Wise direction, the movement of the disk beglimpses by the observer is less than the angular displacement of one of such teeth 17. It will be apparent, therefore, that by the use of the method and apparatus described,

the observer will be able to instantly detect 7 of the projections whether such speed is too high or too low, he may intelligently proto correct the defect. r f .Q

It will be obvious that for the tuning fork shown and described herein there'may be substituted any other device by which a slit opening could be presented before the observer with a frequency as in the case assumed, for example, of per "second; It will also be obviousthat theinve'ntion may be adapted to any desired maximum or; I

nunimum'speeds of rotation, and-thatthe,

number of projections stamped or printed upon the card or disk may be changed either Y with or without-a corresponding change in lent device. Furthermore the invention is Proximates, a certainspeed f i v j is isg 1 1. An indicator used in combination with l: I a strobo'scope for determining the speed. of Q calling devices for automatic telephone' exchanges, marked with iafseries' of'. circumfer entially' "arranged; indications, I and suitablvfi e tel i mounted on the rotating dial device.

the periodicity 'of the tuning fork or equiva i determine the peed of rotation is, crap- 11] 2. An indicator used in combination with a stroboscope for determining the speed of.

calling devices for automatic telephone exchanges; marked With two series of circum- 5 ferentially arranged indications of different number per sector, and suitably mounted 'on the rotating dial of the calling device.

In Witness whereof, I hereunto subscribe my name this 23rd day of December A. D.,

1914:. 1 ARTHUR H. ADAMD'.

Witnesses:

E. EDLER,

K. L. STAHL. 

